Seems some of them would start with depopulation

But this is precisely what at least some Greens object to. What they want, as they frankly admit, is decarbonisation, deindustrialisation and depopulation. They regard the various advances we've made since the old stone age – the coffee, the computers, the cathedrals – with regret. What society needs, they tell us, is not green consumerism, but less consumerism. Which is, of course, precisely what most Western countries have had since 2008. The crash brought about all the things that eco-warriors had been demanding: lower GDP, less consumption, a decline in international trade. Yet, oddly, when it happened, they didn't seem at all satisfied. There's no pleasing some people.

Which directly connects with this:
Ofgem warned there could be energy shortages in the middle of this decade as the UK has failed to build enough new wind farms and nuclear powers stations to replace old fossil fuel plants. 

 It also believes demand for energy may not fall as much as originally expected, as fewer households are insulating their lofts and switching to green appliances than predicted. 

Ministers are so concerned that factories and large businesses may be asked to switch off their power during energy emergencies in return for compensation from bill-payers. 
"We aren't making sure there's enough capacity, so if companies have to shut down we'll rob the average consumer and use that money to pay them off."
The supply crunch is the result of Britain forcing old coal and oil plants to switch off in favour of new green wind farms and nuclear plants.
"We need more bird cuisinarts!"
Ministers are trying to encourage companies to spend more than £100 billion on new green energy infrastructure by offering huge subsidies.
There's that 'steal someone else's money to use for bribes' again.

And here's where you get to the real Green agenda:
If Britain substantially reduced its energy demand, in line with new National Grid forecasts, then the risk of blackouts could remain close to Ofgem's previous estimates at around one-in-12.
There is NO FREAKING WAY they can 'substantially reduce energy demand' to the level they want and have a strong economy.  Or prevent people freezing in the dark.
And at least some of them damn well know it.